1. Field of the Invention
The invention relates to a method and a device for stripping cable and wire end sections, in particular electrical or fiberoptic cables having a coaxial structure.
2. Discussion of Relevant Art
Such methods and devices have long been known. EP-B-195932 describes a type of stripping device frequently used world-wide. This structure comprises--in contrast to stripping devices for stripping continuous cables--essentially clamping jaws, centering jaws, knife jaws and a stop for the manually fed cable end section which is to be cut into and stripped--in particular in a plurality of stages. The stop performs the function of a length adjustment for the cable end section and the function of detecting that the cable end section has passed through the pre-set length and thus rests with its end against the stop, a specific distance from the clamping jaws. The stop is accordingly connected to a stop sensor.
In a further development of this structure, the stop sensor was dispensed with and instead a step was offered in which the knives or centering jaws were closed in a predetermined axial position before the insertion of the cable end section, and the cable end section could thus abut the closed knife jaws or centering jaws. Since the knife jaws or centering jaws were moved beforehand to the corresponding longitudinal position, comparably to the stop according to the EP-B, the knives and centering jaws thus fully performed the length adjusting function for the cable end section. In these two known methods and devices, no length measurement was carried out but an active pre-setting of the length with the aid of a stop or with the aid of the centering and/or knife jaws acting as a stop.
Another structure for processing continuous cables is disclosed in U.S. Pat. No. 5,522,130. A combination of light barriers and controlled drive (measuring) wheels permits positioning of the cable length relative to stationary knives.
Another method for determining the length of cable end sections or another device is described in EP-A-673099. In the case of this structure, the cable end section to be processed is introduced into the stripping device and is held there in its current axial position, which is not exactly predetermined. The actual length is then scanned by means of a scanning arrangement which is displaceable--in the longitudinal direction of this cable end section and relative to said end section--toward the free end thereof and is formed by the closed centering jaws sliding on the cable surface, and the length of the clamped cable end section is thus measured.
Whereas in the first method a length adjustment but no true length measurement is performed, in the second method a length measurement is carried out on the randomly inserted cable end section fixed in the axial position.
Both known methods have characteristics in need of improvement. The method first described is difficult to use in the case of relatively soft cable end sections. Although the method described secondly attempts to overcome this disadvantage, it is difficult to use precisely in the case of soft and thin cables. In particular, soft insulations on cable can be displaced axially relative to the conductor so that the measurement may be erroneous.
Moreover, the additional step of the length measurement in the second method delays the stripping process in comparison with the method first described.
Although a further development of the second method by the Applicant (CH-2053/96, not yet published, and WO-98/08283) improved the measuring problem in the case of soft cables having soft cable sheaths, it did not lead to accelerated stripping compared with the first method.